It is known to inject liquid fertilizers into water streams to be fed to crops.
One known type of injector is sold under the ANDERSON trade mark. This Anderson injector system has a water meter which produces a hydraulic pulse for every unit volume of the water stream. The hydraulic pulse is used to simultaneously cause a number of dosing pumps to stroke once whereby each injects one of their respective doses of liquid fertilizer into the water stream. Each pump has a calibration dial to vary the volume of the dose of the liquid injected by that pump. In use, the calibration dials are pre-set and each pump will inject one dose of liquid for each unit volume of water to achieve the desired proportions and concentrations in the resultant water stream.
The Anderson injector system suffers the disadvantage that varying of the relative proportions of the nutrients requires manual manipulation of the calibration dials. The calibration dials suffer the disadvantage that they imprecisely set the amount of fertilizer liquid injected. Inaccuracies involved in respect of use of the calibration dials are sufficiently large that precise injection of desired doses cannot be ensured. The calibration dials are also difficult to adapt to automated control and change.
Other known fertilizer injector systems require premixing of liquid fertilizer in two tanks and then injecting selected doses from each tank into a water stream. This has the disadvantage that the relative proportions of the nutrients are to a large extent pre-set by their relative proportions in the two tanks.
Known fertilizer injector systems suffer the disadvantage that they are not adapted to facilitate automated precise control and change of injection requirements.
In growing of crops in greenhouses, it is known to control the climate in the greenhouse with a view to achieving desired crop growth and productivity. It is known to monitor greenhouse environment conditions such as air temperature, relative humidity, air carbon dioxide concentration and luminescence and to provide automated control for at least some of these factors as by use of computers. Automated climate control systems for greenhouses do not have the capability to automatically vary the application of fertilizers to the crops on an element by element basis.